set

Sets key to value in dotenv content and returns the new content.

The first existing assignment of key is replaced in place and any later ones are dropped; when there is none, a new line is appended. Every other line (comments, blank lines, other variables) is left untouched, and the replaced line keeps its line ending. value is quoted and escaped only when needed, so get reads it back exactly.

Import

use helpers4::env::set;

Cargo feature env (enabled by default). To compile only this module:

cargo add helpers4 --no-default-features --features env

or in Cargo.toml:

[dependencies]
helpers4 = { version = "0.0.5", default-features = false, features = ["env"] }

Signature

pub fn set(content: &str, key: &str, value: &str) -> Result<String, InvalidKeyError>

Parameters

Parameter	Type	Description
content	&str	The dotenv text to edit.
key	&str	The variable name to set.
value	&str	The value to assign to key.

Returns

Result<String, InvalidKeyError> — Ok on success, otherwise an Err: see Errors.

Errors

Returns InvalidKeyError when key is not [A-Za-z_][A-Za-z0-9_]*.

Examples

use helpers4::env::set;

let updated = set("# config\nHOST=old\nPORT=80\n", "HOST", "example.com")?;
assert_eq!(updated, "# config\nHOST=example.com\nPORT=80\n");

assert_eq!(set("A=1\n", "B", "two words")?, "A=1\nB=\"two words\"\n");

Error type: InvalidKeyError

The variable name passed to set is not a valid name ([A-Za-z_][A-Za-z0-9_]*).

use helpers4::env::InvalidKeyError;

pub struct InvalidKeyError { /* private fields */ }

InvalidKeyError::key

pub fn key(&self) -> &str

The rejected name.

Returns

&str — The rejected variable name.

Source

src/env/set.rs